A system and a method comprise an upstream chamber is configured to receive a variable input flow of a wastewater mixture having a maximum input flow rate. A downstream chamber is adjacent to the upstream chamber. An effluent baffle wall separates the downstream chamber from the upstream chamber. An effluent flow port is located in the effluent baffle wall. The effluent flow port comprises a first orifice configured to produce a first modulated flow of the wastewater mixture from the upstream chamber to the downstream chamber, and a second orifice being positioned above the first orifice. The second orifice is configured to produce a second modulated flow having a second flow rate, wherein a combined flow rate including the first and second flow rates is less than the maximum input flow rate.